AggieMike’s Multi Engine questions…

AggieMike88 said:
In the texts and different videos, the term "light twin" is used.

At what weight does the aircraft become a "heavy twin" and what might be an example at the low end of that spectrum?
Click to expand...

Never seen it defined. Seems to be slang for “Not Part 23”.
 
MauleSkinner said:
12,500# is generally where certification rules change, and it’s no longer a “light twin”, although I think there are some things that change at about 6000#.
But as you’ve probably noted, there is no official FAA definition of that.
Click to expand...

See here is something we agree on. :)

Specifically the requirements for certification to document single engine climb/descent rate, is dependent upon
  • Being above or below 6,000 lbs gross
  • stall speed.
But I would still argue that a piston twin over 6,000 is a light twin. With no definition, I'd draw the line above 12,500. Where the rules and requirements are different.

https://www.faasafety.gov/files/events/GL/GL05/2007/GL0514254/Climb_Performance_Requirements.pdf

Climb Performance Requirements
The current 14 CFR Part 23 single engine climb performance requirements for reciprocating engine twins are as follows: More than 6,000 pounds maximum certificated takeoff weight and/or Vs0 more than 61 knots: The single engine rate of climb in feet per minute at 5,000 MSL must be equal to at least .027 Vso squared. For twins type-certificated on February 4, 1991 or thereafter, the single engine climb requirement is expressed in terms of a climb gradient, 1.5 percent. 6,000 pounds or less maximum certificated takeoff weight and Vso 61 knots or less: The single engine rate of climb or climb gradient at 5,000 MSL must simply be determined. The rate of climb could be a negative number. There is no requirement for a positive single engine rate of climb at 5,000 feet or any other altitude. Rate of climb is the altitude gain per unit of time, while climb gradient is the actual measure of altitude gained per 100 feet of horizontal travel, expressed as a percentage. An altitude gain of 1.5 feet per 100 feet of horizontal travel is a climb gradient of 1.5 percent. With regard to climb performance, the light twin with one engine inoperative will perform marginally at best, and may not be capable of climbing at all under existing conditions. There is no requirement that a light twin in the takeoff or landing configuration be able to maintain altitude, even at sea level, with one engine inoperative.
 
Since we are truly talking “multi” and not “twins” too... look up the margins for three and four engine aircraft climbs sometime after a V1 cut.

After you read them you’ll want to fly on the twins and you’ll never make another ETOPS joke ever again. Hahaha.

“Oh look. If we fly it perfectly we’re guaranteed to clear the airport fence by 15’... sounds ... safe...”
 
denverpilot said:
Since we are truly talking “multi” and not “twins” too... look up the margins for three and four engine aircraft climbs sometime after a V1 cut.

After you read them you’ll want to fly on the twins and you’ll never make another ETOPS joke ever again. Hahaha.

“Oh look. If we fly it perfectly we’re guaranteed to clear the airport fence by 15’... sounds ... safe...”
Click to expand...
I had my chief pilot, director of OP’s, and another guy in my Maule one time when we had to reposition some jets. After taking 10 miles to climb to 1000 feet, I was accused of trying to wipe out half the flight department. I informed them that we were 40 feet higher at ten miles than they plan for most takeoffs in the jet. :cool:
 
AggieMike88 said:
I'll take the ASA book.

Are you craving any Texas created items? Happy to send you a care package as a thank you.
Click to expand...

I got your note with address and then Comcast proceeded to bend me over the railing last night and today in the middle of a four security meeting (audit) day.

I’ll get er shipped out tomorrow hopefully.

This message brought to you by some Comcast tech somewhere who copied the config directly from one Adtran device to another at two separate locations... which has a tendency to send some percentage of your calls to your emergency route when there literally isn’t a phone system at the second site yet. Haha.

“Hey Nate, why are some callers getting the company main menu and then ending up in the wrong call center queues?”

Well look at that... there have been 30-50 calls a day arriving via the emergency route... since Apr 1... nice joke Comcast. LOL
 
ja_user said:
Adtran, that's old school.
Click to expand...

They work and have nearly zero security issues and uptimes measured in years. I assume that’s why Comcast uses them. It’s definitely why we speced them for a couple of links where we own the hardware.

Can pick them up for less than $150 on eBay and they’ll happily sell service contracts (to get latest firmware) on used gear — unlike a certain famous router company who’ll charge thousands up front abd per year and will only support new ones... and can’t maintain those uptimes.

The only downside is the kids may have to read a manual and not just Google to find config examples. LOL.
 
Lesson #2 completed. Getting better at managing a busy airplane.

I figured out Short Field landings in an Aztec. Just as the 1000-footers pass beneath nose, pull power levers to zero and allow aircraft to transform into a brick.

Mentioned this to instructor who responded, "Naaww, a brick is more aerodynamic"

Lots of one engine activity, including on climb out, on runway, in pattern, and on an instrument approach.

Also got first go-around coming home because tower was a little off her game setting us up following a C150 who was being extra pokey and we were overtaking by 40+ knots even with power really dialed back.

Took it in stride and enjoyed the extra 0.15 of money burn.
 
Jim Carpenter said:
Yes, you'll be wondering why they don't just charge you half the usual hourly rental rate on that Aztec.
Click to expand...
I know, right?

2 lessons so far (#3 tomorrow if weather cooperates) and that right engine has failed completely each lesson either full or partial.

You would think this well regarded flight school would fix that.
__________

Even so, I’m impressed at the performance of the Aztec during OEI operations. I get now why it’s a solid choice for schools wanting a trainer or owners who need two engines and decent overall performance
 
AggieMike88 said:
Even so, I’m impressed at the performance of the Aztec during OEI operations. I get now why it’s a solid choice for schools wanting a trainer or owners who need two engines and decent overall performance
Click to expand...

You should sched an XC up here on a 90F day to see it not perform as well. Ha.

Hopefully USPS actually delivers your fun package today. I haven't looked at the tracking.
 
denverpilot said:
You should sched an XC up here on a 90F day to see it not perform as well. Ha.

Hopefully USPS actually delivers your fun package today. I haven't looked at the tracking.
Click to expand...
Arrived Saturday. Thanks!
 
MauleSkinner said:
And since they now cause the same yaw, wouldn’t both engines be critical?
Click to expand...
ja_user said:
A very common question. The Definition is the engine that "causes the most adverse yaw", so no Critical engine if they are the same.
Click to expand...

I've also heard people describe the Seneca (where both engines rotate inward) as having NEITHER engine be critical, while a P-38 (which had both rotating outward!) as having BOTH engines be critical. And that made sense to me...

MauleSkinner said:
12,500# is generally where certification rules change, and it’s no longer a “light twin”, although I think there are some things that change at about 6000#.

But as you’ve probably noted, there is no official FAA definition of that.
Click to expand...

Incorrect... It's just very obscure, in FAA Advisory Circular AC 23.1309-1E:

Class I: Single piston aircraft under 6,000 pounds
Class II: Turbine and multi piston under 6,000 pounds
Class III: Part 23 aircraft over 6,000 pounds
Class IV: Commuter category (Part 25) aircraft

ja_user said:
Specifically the requirements for certification to document single engine climb/descent rate, is dependent upon
  • Being above or below 6,000 lbs gross
  • stall speed.
But I would still argue that a piston twin over 6,000 is a light twin. With no definition, I'd draw the line above 12,500. Where the rules and requirements are different.
Click to expand...

Meh... Usually when we say "light twins" it's in regard to their potential inability to climb in an OEI scenario. Since the over-6,000 crowd at least has a requirement to climb sometimes, I think a separate class is warranted. A 310 or P-Baron is going to do much better than a Twin Comanche or Seminole.
 
flyingcheesehead said:
Incorrect... It's just very obscure, in FAA Advisory Circular AC 23.1309-1E:

Class I: Single piston aircraft under 6,000 pounds
Class II: Turbine and multi piston under 6,000 pounds
Class III: Part 23 aircraft over 6,000 pounds
Class IV: Commuter category (Part 25) aircraft
Click to expand...
I don’t see the term “light twin” in there...
 
Does the Aztec have a feather accumulator as part of the propeller system?

D6682E97-8448-43CB-B8B2-8FFEE0E109DC.png

I'm not seeing mention of it in the owners manual the school has placed online. I'll ask my instructor in addition to you guys.
 
AggieMike88 said:
Does the Aztec have a feather accumulator as part of the propeller system?

I'm not seeing mention of it in the owners manual the school has placed online. I'll ask my instructor in addition to you guys.
Click to expand...

Ive never seen one that does.
 
After 2 days of rain causing 2 lessons scrubbed, had lesson #3 today.

Now we are in the phase where I have seen and experienced everything and it’s time to make it all click and become efficient, deliberate, and smooth.

Today was good for that because at the start, I was a bit hesitant in a few areas and off my game. But as the lesson proceeded, I got better and the instructor was also happier.

Check Ride confirmed for afternoon of June 7. Hoping the recent weather pattern goes away and allows Monday to be a nice VFR day.
 
Last edited:
As we do training and practice the different OEI scenarios, my instructor will guard the throttle quadrant with her hand after doing what is needed to initiate the scenario. This is to keep me from pulling a lever to far during my “working the problem” and cause an emergent situation.

And totally makes sense why she does it and should do it.

My question this morning is, in a two crew member operation (say Part 135 operators), is this same practice done?
 
AggieMike88 said:
As we do training and practice the different OEI scenarios, my instructor will guard the throttle quadrant with her hand after doing what is needed to initiate the scenario. This is to keep me from pulling a lever to far during my “working the problem” and cause an emergent situation.

And totally makes sense why she does it and should do it.

My question this morning is, in a two crew member operation (say Part 135 operators), is this same practice done?
Click to expand...
Normally in a two-pilot operation, one will guard the good while the other pulls back the failed side.

I'm not really sure what the purpose is for your instructor doing it...part of the process is recognizing if you’re pulling the wrong lever and pushing it back up.
 
MauleSkinner said:
Normally in a two-pilot operation, one will guard the good while the other pulls back the failed side.

I'm not really sure what the purpose is for your instructor doing it...part of the process is recognizing if you’re pulling the wrong lever and pushing it back up.
Click to expand...

During low level engine failure scenarios, I will very much guard the levers. But up high, for the engine shutdown stuff, hey, pull the wrong one and see what happens... (I'll actually stop them before that point, but I don't physically block the levers as closely like at low altitude).
 
ja_user said:
The "Right Engine is Wrong"...

Meaning the right engine on a Seneca is replaced so that there is no critical engine. Remember Critical doesn't mean important, it just means means losing it causes the most Yaw
Click to expand...

And roll,

Critical engine factors
P factor, Spiraling slipstream = yaw
Torque , accelerated slipstream = roll

Non conventional twins do not have a critical engine.

If you want I have two Multi guides for a Seminole if you want it. Just message me your email they are too big to attach here.
 
AggieMike88 said:
As we do training and practice the different OEI scenarios, my instructor will guard the throttle quadrant with her hand after doing what is needed to initiate the scenario. This is to keep me from pulling a lever to far during my “working the problem” and cause an emergent situation.

And totally makes sense why she does it and should do it.

My question this morning is, in a two crew member operation (say Part 135 operators), is this same practice done?
Click to expand...
I was taught NOT to do that -- or more accurately, not to make it obvious. Hand at the end of the knee ready to go, but not actively up behind the levers. Never anything in your hands while doing it. (Well that's CFI in general too. You'll learn to drop things real damn quick if you're dumb enough to decide a student has the approach nailed -- because that's when theyl inevitably screw it up. Hahaha...)

Guardimg can give the student too many hints. It's already bad enough they can see it unless you've pulled the old fuel cutoff trick.

And you rarely do the fuel cutoff trick. Some would say never.

You need plenty of altitude and a guaranteed OEI landing location you KNOW you can make, even if the student can't, to play that game.

The assumption must be you're not getting it back once it quits if you choose to "go there".

Suuuuuper highly experienced ME instructor only pulled that trick on me once. In a very good position to do it. He felt it was important to see it once for each MEI student.

He didn't feel it as important for a regular ME student -- but would if the opportunity arose to do it in relative safety.

Levers all the way up and one conks out. It does feel different.

NEVER do it to a new student. Always very late in the training.

Another way to somewhat simulate the visual difference is to block the student's view of the quadrant. Cardboard, a chart, paper, whatever.

They'll still be able to feel the levers but at least the first time it's mildly disorienting enough that they'll revert back to a proper power check and foot verification.

It only works well the first time though. Surprise.

Use it to add a "realistic distraction" to the fairly practiced flow.

If they were accidentally relying on their eyeballs it'll expose it.

Even if they've read this post with the deep dark MEI secrets in it. Haha.

If you're ever really high on an XC and right over a quiet airport and the weather is perfect and your instructor in a Seminole acts like he's messing with his seat belt...

... an engine is going to quit in about 30 seconds or so, and he will already be back to acting like he's looking out the right side enjoying the view.

Lol. It takes a while.

Whether I'd recommend it... Probably not. Whether he could pull it off for years and years flawlessly...

Definitely. Hahaha.

Plus you can use it to make the student read the precautionary engine shutdown checklist since nobody ever seems to bother with that one... :)

"Why is that item about shedding electrical load on there? ... (Blank stare...)... What does the ammeter say?" Heh.
 
RussR said:
During low level engine failure scenarios, I will very much guard the levers. But up high, for the engine shutdown stuff, hey, pull the wrong one and see what happens... (I'll actually stop them before that point, but I don't physically block the levers as closely like at low altitude).
Click to expand...
Amen! ... sayeth the self-preservation minded assembled CFI masses! Lol
 
denverpilot said:
And you rarely do the fuel cutoff trick. Some would say never.

...

The assumption must be you're not getting it back once it quits if you choose to "go there".

Suuuuuper highly experienced ME instructor only pulled that trick on me once. In a very good position to do it. He felt it was important to see it once for each MEI student.

He didn't feel it as important for a regular ME student -- but would if the opportunity arose to do it in relative safety.

Levers all the way up and one conks out. It does feel different.

NEVER do it to a new student. Always very late in the training.

It only works well the first time though. Surprise.

Use it to add a "realistic distraction" to the fairly practiced flow.

If they were accidentally relying on their eyeballs it'll expose it.

Even if they've read this post with the deep dark MEI secrets in it. Haha.

If you're ever really high on an XC and right over a quiet airport and the weather is perfect and your instructor in a Seminole acts like he's messing with his seat belt...

... an engine is going to quit in about 30 seconds or so, and he will already be back to acting like he's looking out the right side enjoying the view.

Lol. It takes a while.
Click to expand...

I do the fuel selector cutoff for the “engine failure in cruise” scenario routinely. Like once or twice a flight starting on Lesson 2. Now, the first time, I do brief them, and tell them when I do it, so that they can see that while it is important to do the required actions, they do not need to panic and overreact - rather, pause and think about it for a second. Later in training I will do the “mixture to cutoff” method, but that’s really only because that’s how the examiner is going to do it, so I want them to see it a couple times.

We’re at or above 4000 AGL when we do this, IAW the Seminole POH. That's 5500 MSL in my area. If for some reason the engine doesn’t start back up, we’ll just fly back home and land. We can maintain 4500 with a feathered prop just fine, and the ground is around 1200 MSL.

I consider the “fuel selector off” method to be the absolute most realistic way to simulate an engine failure in this airplane, at cruise altitude. The trainee can’t see you do it, by the time the engine fails I’m already babbling about some other topic, and it catches them by surprise, like it should. Doing it with the mixture or throttle just doesn’t simulate it well, nor does it prepare the trainee for the real thing - they can see the engine failure coming as you move your hand up.

Now, down low, I use throttle only, there’s no other safe way to do it.
 
I am in the process of creating my own study guide for the oral exam.

Included will be a to the point outline of what Vmc is, what factors affect it, and why those factors affect it.

I also wanted to include the references from the FAR for this.

Existing textbooks point to §23.149, which did cover just about all of what I'm packing into the brain.

But recently Part 23 must have underwent a big revision including updating the number schema.

Any help on what new Sections cover the same ground that .149 did?
 
Check ride is a week from Monday and I'm building a oral exam study reference sheet.

One area I'm memorizing are the V-speeds for this Aztec (PA-23-250). But within the ancient POH, I'm not finding one that I want to have on my sheet: VSSE

From the PHAK in case it helps answers the question
Pilots Handbook of Aeronautical Knowledge said:
VSSE—safe, intentional OEI speed—originally known as safe single-engine speed, now formally defined in Title 14 of the Code of Federal Regulations (14 CFR) part 23, Airworthiness Standards, and required to be established and published in the AFM/POH. It is the minimum speed to intentionally render the critical engine inoperative.
Click to expand...

Or could the POH have it disguised as a different value or name since it was written so long ago?

Any chance another Aztec owner can point out where to find it?
 
It’s been a long time since I have flown light twins but I thought Vsse was the same as Blue Line.
 
AggieMike88 said:
Check ride is a week from Monday and I'm building a oral exam study reference sheet.

One area I'm memorizing are the V-speeds for this Aztec (PA-23-250). But within the ancient POH, I'm not finding one that I want to have on my sheet: VSSE

From the PHAK in case it helps answers the question


Or could the POH have it disguised as a different value or name since it was written so long ago?

Any chance another Aztec owner can point out where to find it?
Click to expand...

VSSE didn't exist back then. Doubt it's in any CAR 3 aircraft.

Greg Bockelman said:
It’s been a long time since I have flown light twins but I thought Vsse was the same as Blue Line.
Click to expand...

It's usually between VMC and VYSE.
 
Add 10% minimum to VMC, if not actually published. Now ask yourself, why is this important and to whom?
 
As @dmspilot indicated, it’s probably not in your POH. In most of the Beech products I’ve flown it’s Vmc+5, but that doesn’t mean it would be a valid gouge for the Aztec. Your instructor should probably have a number that he’s been using.
 
You must log in or register to reply here.
Back
Top